Electric heater.



.I. LAWRENCE.

\ ELECTRIC HEATER. APPLICATION FILED NOV- 19, 1915;

1,177,254. I f Patented Mai. 28,1916,

2 SHEETS-SHEET l.

ATTOIRNEYSII,

J. LAWRENCE ELECTRIC HEATER.

APPLICATION FILED NOV. 19, 19 15- Patentegl Mar. 28, 1916.

2 SHEETS-SHEET 2- INVENTOR JAMES LAWRENCE, NEW YORK,

very subject of the Kin STATES PATENT OF ICE.

EnEoTEIc HE ATER.

To all whom it may concern:

Be it known'that 1, JAMES LAW ENCE, a

of Great Britain, and-a resident of New ork city, .in the county andState of'NeW York, have invented certain new and useful Improvements inElec-f tric Heaters, of which the following is a specification.

My invention relates'to electric heaters, andparticularly, to that typeof heaters which includes heating units comprisingresistance memberscarried by a supporting body.

coils. So far as the transference of electrical energy to heat isconcerned, this method has proved highly efficient. But heretofo re thedevice's designedfor utilizing the heat "generated from the resistancecoils has been ineflicient. It is well'known that the rate ofheatradiation from a body increases in-greater proportion than the intensityof the temperature of that body, and therefore in my device it is myintention that'the heating elements shall be kept at the highestpossible intensity of temperature, even though the elements may therebybe consumed; and in order to overcome the inconvenience due to'theburning out of the elements, I intend that the elements shall be.readily replaceable. A welLknown fault present in the electric heatingunits of this day is. that a great'amount of heat gener-' ated by theheating elements is' absorbed by the member'which supports the heatingele-' ment. In'my device, therefore, the support for the heating elementis made with'a mini mum cubicalcontent, so;that while'it su-ffisistanceelement, to the body tobe heated, the

plate having the minimum cubical content consistent with practicalconsiderations Specification of Letters Patent;

- heating unit .of this specification,

Another object is to provide simple,

N. Y., ASSIGNOR 'ro s'rANnEY e. RANGER, or NEW YORK,

. Patented Mar. 25;, 1916'. Application filed November 19, 1915. SerialNo. 62,313. 5

economical and practical meansfor securing an electrlc heating elementto a supporting body to form a heating unit.

Another object is to fprovi' heating-unit" which is complete andincludes electrodes for the introduction of electric current and whichis adapted to be removmember. 1

Another object is to provide a heating unit comprising a heating elementsupporting ably operatively positioned in a receivmg do an electricplate having means for draining away from I the heating element'materialspilled over the unit.

Another object is to provide a heating unit comprising. a heatingelement .and a plate forsupporting. the element and provided with meansto' secure a circulation of heat generated by the element.

Another object istoprovide a receiving member for an electricalheatingunitwhich perature variations.

Another object is to provide a receiving member. for anelectricalheating unit, the

having. electrodes for the in-' .troduction of electricity and therec'elvlng member having spring contacts for accomis durable andresistant to the effect of temmodat-ing the electrodes of a heating un1telectricity to the unit, said receivd pp y also being provided withmeans in-g member for protecting the contacts from the heat generated by.the unit 'spilled over the unit. 1,

.Another object"'isto provide, a heatingunit and a receiving membertherefor, the .unit and member being formed to and from materia'lprovide" m'eansjfor preventing. heat frombei'ng con= Y ducted from theun1t to the receivingmember. Y Another object isto providea'jfsupportfor .anelectric heating unit receiving member whereby a. completeelectric heater. is pro vided'wh'erein the heating units are read lyinterchangeable.

Other and further objects and advantages of my inventionfwill'b'edisclosed in th'e' following descriptiontaken in connect on with theaccompanying drawings forming a part in the claims. I I

Inthe drawings, in whichlike reference and will be pointed out ing myinvention; Fig. 2 is a partial crosstions of heating unit receivers.

The electric heater which is illustrated by the drawings and describedin this speciflcation is one embodiment of my invention and is describedfor purposes of interpretation thereof. The top plate 1 of the heater,together with the legs 2 attached thereto, comprises a support for theheating unit receiver 3, and the heating unit receiver carries theheating unit plate 4 on which I there are mounted heating elements 5.The

top 1 of the heater has a circular opening therein, andto the top aresecured brackets 6 upon which rest the circular receiving member 3,which is slightly smaller than the hole in the top 1, thereby leaving anopening 8 between the top of the support and the receiver 3, so that airmay circulate through the opening to prevent the conduction of heat fromthe receiver to the support. The upper surface of the top 1 is shown byFig. 2 tobe slightly above the upper surface of the receiver 3, so thatheavy articles placed upon the heater may be supported by the strongsupporting member rather than by the heating member 4 which is ofrefractory material. The difi'erence in the level of the upper surfacesof the receiver and the top 1 also permits receptacles which are warpedto be placed into close contact with the heating plate 4. The heat ingplate 4, as shown by Figs. '8 and 9, is a circular member havingopenings 9 and a cross bar 10. The openings may be large as shown inFig. 8, in which case the rim is provided with slots 11 to relievestrains arising in the circular portion by reason of variation in thetemperature ofthe-receiving member. The openings 9 may be small as shownin Fig. 9,:and the receiving member is made in three parts, 3*, 3 and 3,and variations in temperature will not cause its destruction. Within theupper surface it the receiver there is a circular opening,

jacent the wall of this opening there is formed in the receiving membera supportingledge 12, and upon this ledge the heating unit 4' issupportedso that its upper surface is practically flush with the uppersurface of the receiver, but it is to be understpod that I do notconfine myself to the detailed arrangement .described.

Either upon the ledge or upon the lower face of the plate 4 of theheating element projections 13 are formed which elevate the plate 4above the ledge. The plate 4 is made smaller than the opening in thereceiving cal coils of suitable resistance wire of such,

material and dimensions that it will be heated immediately toincandescence without a great initial rush of current when the currentis turned on, and will be kept at a destructive temperature therafter.The plate 4 is of refractory material and so designed that they arereadily replaceable because the heating element is operated at adestructive temperature. It is designed to have the minimum cubicalcontent possible without substantial loss'of strength, so that heat ofthe heating element will not be taken from the article to be heated whencurrent is first turned on, or stored up to be wasted after the currentis turned off. The opening atthe top of the grooves is entirelyunobstructed and it will be seen from the shape of the grooves that theradiation from the heating element will be the freest possible toobtain, and that absorption of heat by the sides of the groove will bealmost negligible.

The ends of the heating element near the edges ofthe plate are passedthrough openings in the plate, as are also the ends of the elements atthe center. To the back of the plate at the edges and at the center, asclearly seen in Fig. 2, there are secured electrodes 15 which extenddown through holes 16 in the cross bar 10 of the receiving member 3.Secured to'the lower face of the receiving member, by bolts 18, thereare contact supporting bars 17. On each of these contact supporting barsthere is mounted a spring clip 19 which, asshown in Fig. 2-,accommodates one of the electrodes 15 when the heating'unit is droppedinto the opening in the receiving member. Binding posts 20 from anymaterial which may pass through the drain holes 32 a plurality of whichextend through the plate 4 from the bottom of the groove therein.

In the upper surface of the receiving member there are formed grooves 21so that the heating unit,plate 4 may be grasped by the fingers to removeit. In the upper face of the heating unit plate there are providedradial grooves 22 which intersect the grooves in which the heatingelements are positioned. This is to permit circulation of heat acrossthe face of the heating element when only one of the two concentricspirals of the heating elements is radiant.

It is old to retain the heating element in its groove by formingprojections extending from the top edge of the walls of the groove outover the heating element. These projections I have done away with, inorder that all of the heat may radiate directly to the article tobeheated, and I have shown several methods of anchoring the heatingelement within its groove. In Fig. 3 I have shown a preferred form ofheating element anchor. The heating element is formed with long loops ofwire 24 which pass through openings 25 through the plate in the bottomof the groove. The long loop 24 is then spread out into the wide loop 26and subsequently flattened into the knot of wire 27 shown at the rightof Fig. 3. By anchoring the heating unit in this way a negligibleportion ,of the heating unit. is covered by the plate andat the sametime a very simple and efficient anchoring means is provided. In Fig. lI have shown an anchoring means which consists in a loop of wire passedthrough one hole in the plate over one loop of the heating element andback through another hole in the plateand knotted to prevent loosening.In Fig. 5. I have shown a loop of wire passing through a single hole inthe plate and inclosing a loop of the heating element and being knottedto prevent its being pulled through the plate by any strain on theheating element.

While it is old to have a heating element of the type which I employpositioned in a straight groove, the top opening of which isunobstructed, it will be seen that I have devised a heating unit whichincludes a plate having a curved groove the top opening of which isunobstructed and the heating element, which is positioned in the groove,is held from straightening out and positioning the scope of my inventionwhich I desire to be defined only by the hereunto appended claims.

Having thus described my invention, what .I claim as new and desire tosecure by Letters Patent, is

1. As an article of manufacture, a heating itself above the top of thegroove by 1 ,a nchors which hold it. against the bottom of heatingelements,

2. As an article of manufacture, a heating unit comprising a platehaving a continuous groove in one face thereof and recesses'in the otherface thereof and openings extend ing from the bottom of said groovethrough said plate and into said recesses, and a heating 4 elementpositioned in said groove, said ele- 'ment havingloops extending throughsaid openings and being shaped to cooperate with the opposite face ofsaid plate Within said recesses to anchor said element to said plate atintervals throughout the extent of said element.

3. In a device of the class described, a heating unit having electrodesfor the introduction of electricity thereto, a receiving member for saidunit, spring supply contact members for cotiperating with saidelectrodes to deliver current thereto, and means carried by saidreceiving member to protect said contacts from the heat generated bysaid unit.' I

4. Ina device of the class described, a heating unit comprising a bodymember of insulating material and a heating-unit-supporting receivingmember having a recess into which said body member fits and comprising aring and a cross-bar, said ring being split to avoid strains due totemperature variatlon.

5. In a device of the class described, a heating unit comprising a bodymember of insulating material and a heating-unit-supporting receivingmember of refractory ma- I 'terial comprising separated segments of aring and a member oining said segments,

the inner surface of said ring being shouldered to permit said unit torest within said receiving member.

6. In a device of the class described, a heating unit comprising a platehaving a' plurality of grooves in one face thereof, and

respectively positioned in said grooves, said plate having additionalgrooveshaving a cross-section substantially equal to that of said firstnamed grooves; respectively connecting portions of said firstnamedgrooves, whereby heat uniformly when a body rests on said plate.

7. In a device of the class described, a heating unit comprising a platehaving concentric spiral grooves in one face thereof, and heatingelements extending .throughout said grooves, said plate having radialgrooves having a cross-section substantially may circulate insulatingmaterial, a receiving member therefor comprising a ring having ashoulder portion formed on its inner surface to support said plate atits edges, one of said portions being provided with projections forseparating said portions to permit air circulation.

9. In an electric stove, the combination of a removable and replaceableheating unit support, a heating unit comprising a heating element ofsuch construction and resistance as to be raised to incandescencesubstantially immediately upon the passage of a current.

of the voltage for which it is designed, said heating unit being sopositioned upon its support as to permit of the ready removal of suchheating unit and its replacement by another similar heating unit, andelectrical conducting surfaces on the heating unit support and said unitso arranged as to contact with one another and close electricalconnection at such points upon the mere placing of the unit in its placein the support, whereby electrical heating units may be used capable' ofbeing brought to a high degree of heat at once upon the passage ofcurrent and that whenburned out such heating units may be readilyremoved and replaced.

10. In a device of theclass described, a heating unit having electrodesfor supplying current thereto, a supporting member for said unitandhaving perforations through which said electrodes extend, and springsupply contacts with which said electrodes cooperate after passingthrough said supporting member.

11. In a device of the class described, a heating unit having electrodesfor supplying current thereto, a cross-bar passingbeneath said unit andhaving recesses in its lower r face, and openings through said bar intosaid recesses, spring supply contacts in said recesses, said electrodesbeing adapted to extend through said openings to cooperate with saidcontacts.-

12. In an electric heater, a stand comprising 'a top plate andsupporting means therefor, said plate having an opening therein, areceiving member of insulating material supported by said stand withinsaid opening and spaced from the edge thereof, and an electric heatingunit carried by said receiving member and removable therefrom.

.In testimony whereof, I have signed my name to this specification.

JAMES LAWRENCE.

